We are working to minimize power consumption in our battery-powered product. We observed the unexpected behavior that the TPS62175 is consuming slightly more current in SLEEP mode than in normal mode. We'd like to verify that we're using the part properly, or at least have a good explanation for this behavior.
The basic setup:
- input voltage nominal 7.2V
- output voltage 3.3V
- Feedback divider network: 470K / 150K (5.3 uA flowing through the divider)
- Approximately 350 uA load on the output
According to the data sheet, with a load of 350 uA, the part is predicted to have an efficiency of ~75% in SLEEP mode and draw about 4.5 uA quiescent current, compared to ~70% efficiency and 22 uA quiescent current.
But on the input side, we're seeing a load of ~163 uA in SLEEP mode but only ~158 uA in normal mode.
Why is the current consumption higher in SLEEP mode than in normal mode?